Summary
In order to determine the origin of the hypothalamo-amygdaloid connections in the cat, small lesions were placed at various rostro-caudal levels of the hypothalamus. The animals were sacrificed after a period of 4, 8 or 11 days and the brains stained with the Nauta (1957), Fink and Heimer (1967) or Wiitanen (1969) method for the demonstration of degenerating axons and their terminals. It was observed that the anterior hypothalamic nucleus sends a small projection to the medial subdivision of the central nucleus and to the basal and lateral nuclei of the amygdala. The lateral preoptic area sends a larger projection to the anterior amygdaloid area, both subdivisions of the central and basal nuclei, and to the lateral and medial nuclei. No degeneration was observed in the amygdala following lesions in the medial preoptic area, the ventromedial nucleus or the lateral hypothalamic area caudal to the anterior hypothalamic area.
In a series of animals with lateral preoptic lesions, the site of termination of degenerating boutons on neurons of the amygdaloid nuclei was determined and the course of the degenerative process followed over a period ranging from 2 to 15 days. Many of the boutons, especially in the earlier stages of degeneration, appeared to be of the B3 type, containing flattened vesicles and forming symmetrical synaptic contacts with dendrites or somata. With longer post-operative survival times, however, they became increasingly electron dense and shrunken, so that the bouton type could not be determined.
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This paper is a portion of a thesis submitted to the School of Graduate Studies, University of Ottawa, by C. Wakefield in partial fulfillment of the requirements for the degree of Doctor of Philosophy. — The investigation was supported by the Medical Research Council of Canada, Grant M. T. 870. — The authors gratefully acknowledge the technical assistance of Miss E. Korzeniowski and Miss U. Prym.
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Wakefield, C., Hall, E. Hypothalamic projections to the amygdala in the cat. Cell Tissue Res. 151, 499–508 (1974). https://doi.org/10.1007/BF00222995
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DOI: https://doi.org/10.1007/BF00222995